These are not really standards

Draft specifications that have pretty good de facto adoption/agreement:

Desktop Entry specification describing information about an application such as the name, icon, and description. These files are used for application launchers and for creating menus of applications that can be launched.

The startup-notification-spec describes a mechanism to allow desktop environments to track application startup, to provide user feedback and other features.

The Trash specification provides a common way in which all "Trash can" implementations should store, list, and undelete trashed files.

The Autostart specification describes how applications can be started automatically after the user has logged in and how media can request a specific application to be executed or a specific file on the media to be opened after the media has been mounted.

DBPC - DBus for process control is layer above DBUS which define a standard set of objects, interfaces and methods for use in process control. It will provide a common standard for industrial communication, especially between HMI, SCADA and field electronic equipement.

Retracted Specifications

The Desktop Color Scheme specification is a draft specification that defines names for colors to be used for rendering user interface elements. It also provides an algorithm for generating a matching set of colors from a single base color (The colorscheme spec has been pulled on request of its authors).